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📘arr.entries

JS ⟩ objects ⟩ Array ⟩ methods ⟩ entries()

Object.entries() - keys are string-based.
Array.prototype.entries() - keys are integer-based.

💾 replit:

Last updated 3 years ago

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const a = ['a', 'b', 'c'];
    
// ⭐️ keys are "integers"
Array.from(a.entries()),    // [ [ 0, 'a' ], [ 1, 'b' ], [ 2, 'c' ] ]

// ⭐️ keys are "strings"
Object.entries(a),          // [ [ '0', 'a' ], [ '1', 'b' ], [ '2', 'c' ] ]

for(const [i, value] of Object.entries(a)) {
    console.log(i + 1);     // 🧨 雷區：'01', '11', '21' ❗❗❗ 
}